Fishes,  Shell  Fish,  Reptiles, 


And  their  Life  History 


FRANK  OWEN 


indred   Lessons 


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E.  L,  KELLOGG  &  CO., 


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1bow  to  Ueacb"  /Manuals.— No.  16 


HOW  TO   TEACH   ABOUT 

AQUATIC  LIFE 

FISHES,  SHELLFISH,  REPTILES,  AND  THEIR 
LIFE-HISTORY 


BY 


FRANK  O.  PAYNE 

i) 

AUTHOR    OF    "ONE    HUNDRED    LESSONS    IN    NATURE/ 
"HOW    TO    TEACH    ABOUT    TREES,"    ETC. 


NEW  YORK  AND  CHICAGO 

E.   L.    KELLOGG  &  CO. 


IIBH; 


CONTENTS 

CHAPTER  PAG] 

I.  Introductory 3 

II.  How  to  Study  Water-life 6 

III.  How  to  Make  an  Aquarium 8 

IV.  Some  Water-plants 14 

V.  Some  Water-animals 25 

VI.  Metamorphosis 53 

VII.  Some  Amphibians  and  Reptiles 62 


Copyright,  1901,  by 

E.  L,  KELLOGG  &  CO. 

NEW  YORK 


HOW  TO  TEACH  ABOUT  AQUATIC 
LIFE. 


CHAPTER  I. 
Introductory. 

IN  beginning  the  study  of  the  various  forms  of  life 
which  are  found  in  water,  one  discovers  that  they 
are  as  various  and  as  different  as  those  which  live 
in  the  air.  Indeed  one  is  often  led  to  think  that 
water-creatures  are  more  variable  and  more  wonder- 
ful than  the  inhabitants  of  the  air.  This  is  not  the 
truth.  They  seem  curious  because  we  are  not  famil- 
iar with  them.  But  they  are  no  more  so  than  are 
the  creatures  with  which  we  are  most  familiar.  All 
living  things  are  wonderful.  Nay  more,  all  created 
things  are  wonderful.  It  is  not  for  man  to  say 
which  of  all  God's  works  is  most  so. 

But  whether  we  study  life  in  the  water  or  out  of 
it,  one  fact  belongs  to  all  living  things :  All  breathe. 
And  it  is  due  to  their  different  manner  of  breathing 

3 

M75O302 


4 


HOW    TO    TEACH    ABOUT   AQUATIC    LIFE. 


that  the  water-creatures  as  a  class  are  different  from 
those  of  the  air. 

All  living  things  have  a  circulating  fluid  (sap  or 
blood)  which  carries  nutriment  to  the  growing  parts 
and  removes  worn-out  particles  from  wasting  tissues. 
This  fluid  must  be  purified  in  order  to  do  its  work 
and  oxygen  must  be  absorbed  in  order  to  make  it 
pure. 

Now,  the  real  difference  between  air-breathing 
and  water-breathing  creatures  lies  in  the  way  that 
this  oxygen  is  received  into  the  blood. 

Air-breathers  have  lungs ;  water-breathers  have 
gills. 


AIR. 


FIG.  i. — Lung-cell. 


FIG.  2. — Gill  Fringe. 


Now,  lungs  and  gills  do  not  seem  to  be  very  much 
alike,  but  on  close  observation  their  difference  is  not 
so  great  as  would  at  first  appear.  A  gill  may  be 
considered  as  a  lung  turned  inside  out.  In  order 


INTRODUCTORY.  5 

that  the  blood  may  absorb  oxygen,  it  must  come 
into  direct  contact  with  it.  Now,  in  a  lung-cell  the 
blood  flows  on  one  side  of  a  very  thin  membrane 
while  pure  air  is  on  the  other  side,  and  the  oxygen 
and  carbonic  acid  gas  pass  through  this  membrane, 
the  former  to  the  blood  and  the  latter  from  it. 

Now,  it  would  be  too  great  an  effort  to  inhale 
water;  so  the  membrane  is  extended  outward,  bring- 
ing the  blood  into  direct  contact  with  the  pure 
water,  and  the  oxygen  and  carbonic  acid  gas  are 
exchanged  as  before. 


CHAPTER  II. 
How  to  Study  Water-life. 

THERE  are  two  ways  of  studying  the  creatures 
which  live  in  \\ater.  These  may  be  known  as  the 
out-door  way  and  the  in-door  way.  To  these 
may  be  added  a  third  method,  but  as  the  writer  has 
little  use  for  it,  it  will  be  dismissed  with  a  very  few 
words.  I  allude  to  the  study  of  preserved  speci- 
mens. 

Now,  it  cannot  be  denied  that  dried  and  pickled 
specimens  have  their  place.  The  place  of  all  such 
things  is  the  same  as  that  of  reference  books  in  a 
library.  They  are  useful  principally  for  reference. 
But  the  study  of  such  things  is  to  be  discouraged  if 
fresh  material  is  to  be  had,  and  by  fresh  material  is 
meant  live  specimens  when  these  are  at  hand. 

Of  the  two  methods  above  more  may  be  said. 

I.  By  the  out-door  method  is  meant  the  ob- 
servation of  water-animals  in  their  own  environment. 
Surely  nothing  can  be  more  delightful  than  to  sit 
by  the  side  of  a  brook  and  to  watch  the  fishes  as 
they  dart  hither  and  thither  through  the  limpid 

6 


HOW   TO   STUDY   WATER-LIFE.  / 

water.  The  fact  that  the  student  sits  at  the  end  of 
a  fishing-rod  need  not  hinder  his  enjoyment  either. 

To  row  out  upon  the  surface  of  a  shallow  pool  and 
then  to  lie  at  full  length  and  scan  the  transparent 
depths  below  may  look  like  the  acme  of  indolence, 
but  to  the  lover  of  nature  it  is  not  so.  What  trag- 
edies, what  comedies,  what  histories  are  enacted 
and  repeated  in  those  cool  depths  only  they  who 
have  witnessed  them  may  know. 

2.  But  every  teacher  cannot  do  so.  The  streams 
and  pools  with  their  teeming  life  cannot  be  visited 
by  the  whole  school  and  out-door  observation  must 
ever  be  largely  an  ideal  not  easily  to  be  attained. 
So  if  the  school  cannot  go  to  the  pond,  the  pond  at 
least  can  come  to  the  school.  That  is,  a  sample  of 
the  pond  can  come  to  the  school  in  the  shape  of  an 
aquarium.  Indeed  in  many  respects  the  aquarium 
is  the  most  satisfactory  way  for  studying  the  forms 
of  life  which  inhabit  water. 

It  is  small,  convenient,  and  movable.  The  con- 
tents can  be  changed  at  will.  The  time  required 
to  go  to  a  pond  or  stream  is  saved  by  having  the 
aquarium  in  the  room.  Lastly,  the  aquarium  is 
present  for  a  long  time.  It  is  ready  to  be  seen  at 
any  momant,  and  changes  requiring  many  observa- 
tions may  be  seen  at  odd  moments  without  detract- 
ing from  class  exercises  in  other  subjects. 


CHAPTER    III. 
How  to  Make  an  Aquarium. 

THERE  are  two  forms  of  aquarium.  One  consists 
of  a  glass  vessel  into  which  living  animals  are  put 
for  study  or  ornament  and  in  which  there  is  noth- 
ing else  but  water.  Such  an  aquarium  requires 
much  attention,  for  the  water  must  be  changed 
once  or  twice  per  day,  and  even  with  these  pre- 
cautions animals  can  rarely  be  made  to  live  long 
in  such  environment.  Indeed  one  is  strongly  in- 
clined to  declare  that  such  a  thing  is  in  no  sense  an 
aquarium. 

The  better  form  of  aquarium  may  be  called  the 
self-sustaining  aquarium.  It  is  so  called  because  it 
contains  the  right  amount  of  plants  and  animals 
mutually  to  satisfy  each  other. 

It  is  well  known  that  the  very  substances  which 
animals  breathe  out,  plants  require,  and  vice  versa  ; 
so  that  if  an  aquarium  is  stocked  with  both  plants 
and  animals,  both  will  thrive  equally  well.  Let  it 
not  be  supposed  that  an  aquarium  must  be  of  any 
special  shape  or  size.  Any  vessel  of  clear  glass  of 


HOW    TO    MAKE    AN    AQUARIUM.  9 

any  size  or  shape  will  do,  but  vessels  having  straight 
faces  and  square  angles  are  greatly  to  be  preferred. 


FIG.   i. — Glass  Bottle  used  as  Aquarium. 

The  least  desirable  form  of  vessel  is  the  common 
globe.      Its  convex  shape  causes  everything  within 


10        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

to  appear  magnified  so  that  observations  cannot  be 
relied  upon  any  more  than  one's  own  image  seen  in 
a  convex  or  a  concave  mirror. 

The  size  must  depend  upon  the  size  of  the  in- 
habitants. An  aquarium  for  rearing  gnats  and 
mosquitoes  may  be  made  in  a  tumbler.  Dragon- 
flies,  stone-flies,  and  crayfish  do  very  well  in  quart 


FIG.  2, — A  Self-sustaining  Aquarium. 

jars  or  candy-jars,  but  frogs  and  fishes  need  a  great 
deal  more  room. 

For  all  purposes  the  most  satisfactory  aquarium 
is  made  in  cubical  form  and  may  be  had  from  any 
dealer  in  apparatus. 

Having  selected  a  suitable  jar  the  next  step  is  to 
stock  it.  It  is  not  difficult  to  stock  an  aquarium, 


HOW   TO    MAKE    AN   AQUARIUM.  II 

but  it  is  not  always  easy  to  secure  inhabitants  who 
will  live  peaceably  in  it  together.  The  weaker  and 
smaller  creatures  often  become  the  prey  of  the  larger 
ones,  so  that  what  sometimes  is,  in  the  start,  a  very 
thrifty  looking  colony  is  reduced  in  a  few  days  to 
one  or  two  individuals. 

1 .  Place  a  layer  of  clean  coarse  sand  or  fine  gravel 
on    the    bottom    of  the  vessel.      This    is    to    form 
an  anchorage   for  the    roots    of    the    water-plants. 
These  may  be  collected  at  the  same  time  that  the 
animals  are  procured.      A  very  good  way  is  to  pre- 
pare the  vessel  with  soil  and  plants,  add  the  water 
slowly,  and  allow  to  stand  until  the  water  has  be- 
come clear.     Then  place  the  animals  in  the  dish. 
Caution  :    Do  not  have  too  many  of  either  plants  or 
animals.      The  proper   balance  can  only  be  deter- 
mined by  experiment. 

2.  Do  not  try  to  compel  creatures  to  live  in  an 
aquarium    if  they  do  not   naturally    belong    there. 
The  writer  once  saw   an  aquarium  in  which  a  tree- 
toad    was    making    desperate    attempts   to    escape. 
Let  it  be   remembered   that   many  forms  of  animal 
life  pass  their  infancy  in  water,  but  when  they  reach 
maturity  they  live  in  the  air. 

3.  Attend  to  the  amount  of  light  and  heat.      If 
possible,  never  let  the  temperature  rise  above  50° 
Fahr.,  nor  below  35°.      Never  let  an    aquarium  be 
exposed    for   very   long   in   the   direct    sunlight;  a 
shady  place  is  much  to  be  preferred. 


1 2         HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

4.  An  aquarium  must  be  aired  from  time  to  time 
also,  for  the  plants  contained  are  not  sufficient  for 
all  purposes.      It    is   also   an    excellent   idea   to  put 
some    fragments    of    charcoal    in    once    in   awhile. 
These  will  deodorize  the  water  if  any  foulness  has 
arisen  through  the  death  and   decay  of  any  of  the 
inhabitants. 

5.  Always    provide    a    supply    of    water-snails. 
These  creatures  are  herbiverous,  and   their   food   is 
mostly  the  green  slime  which  accumulates  so  abund- 
antly on    the  glass   if  these    animals   are   not   pro- 
vided. 

6.  Let  it  be  urged  as  a  suggestion  that  sea-shells, 
specimens  of  coral,  and  all  sorts  of  impossible  caves 
be  omitted  from  these  aquaria.    There  is  something 
inexpressibly  ridiculous  about  corals,  sea-shels,  and 
all  such  things  lying  in  fresh  water  among  creatures 
with  whom  they  could  not  possibly  have  had  any 
connection. 

Before  concluding  this  chapter  it  may  be  helpful 
to  describe  how  to  catch  water-animals  without  the 
risk  of  injuring  them.  An  ordinary  dipping-net 
made  by  fastening  a  piece  of  thin  netting  over  a 
hoop  fastened  to  a  long  stick.  This  will  do  in  deep 
water,  but  in  shallow  places  a  long-handled  dipper 
or  indeed  an  old  tomato-can  may  be  made  to  answer 
very  well.  Nor  will  one  have  to  go  far  or  wait  long 
before  making  many  captures.  Last  spring  the 
writer  caught  five  different  sorts  of  living  creatures 


HOW   TO   MAKE   AN    AQUARIUM.  13 

without  moving  one  step  in  a  little  stream  half  a 
mile  from  his  home. 


,  3. — An  Ordinary  Dipping-net. 


CHAPTER    IV. 
Some  Water-plants. 

IN  this  chapter  we  will  study  some  of  the  plants 
which  live  in  water  and  which  may  be  grown  in 
the  aquarium.  These  are  Duckweed,  Eel-grass, 
Nitella,  Chara,  and  Potamogeton. 

These  plants  are  particularly  interesting  on  ac- 
count of  the  great  quantities  of  oxygen  which  some 
of  them  give  off  if  placed  where  the  sunlight  falls 
upon  them.  In  fact  the  writer  has  often  caught 
vessels  of  oxygen  by  inverting  over  these  plants  a 
jar  filled  with  water. 

I.  Duckweed  (Fig.  4).  —  This  curious  little 
plant  is  also  called  "duckmeat."  It  grows  abun- 
dantly in  quiet  water  where  its  small  clusters  of 
round  green  leaves  float  upon  the  surface.  If  ex- 
amined there  will  be  found  a  fine  cluster  of  delicate 
threadlike  roots  projecting  downward  from  the 
under  surface  into  the  water.  The  leaves  are  bright 
green  in  color  and  rather  thickish.  If  cut  open  they 
will  be  found  to  be  made  of  a  spongy,  cellular  sub- 
stance full  of  air  spaces.  By  means  of  these  they 

14 


SOME   WATER-PLANTS.  15 

are  able    to   float.     A  small  amount  of  Duckweed 
should  be  placed  in   every  aquarium,  but  not  too 


FIG.  4. — Duckweed. 

much,  since  it  prevents  a  good  view  from  above  if 
very  much  of  this  plant  is  floating  on  the  surface. 

2.  Eel-grass  (Fig.  5). — Eel-grass  is  very  differ- 
ent from  Duckweed.  It  grows  to  the  bottom  and 
has  long  slender  thin  leaves.  The  most  remarkable 
peculiarity  is  the  way  it  takes  to  bring  its  flowers  to 
the  surface  of  the  water.  There  are  flowers  of  two 
sorts  on  this  plant.  One  sort  of  flowers  has  the 
stamens  and  the  other  the  pistils.  Now,  there  are 
no  bees  or  other  flying  creatures  under  water  to 


1 6        HOW   TO    TEACH    ABOUT   AQUATIC    LIFE. 

take  the  pollen  from  one  kind  of  flowers  and  bear 
it  to  the  pistils  of  the  other  sort,  so  nature  does  a 
very  curious  thing.  When  the  staminate  flowers 
are  ripe  tjiey  break  off  from  the  parent  stem  and 


FIG.   5. — Eel-grass. 

rise  to  the  surface.  Here  they  open  and  cast  their 
pollen  on  the  water.  But  the  pistillate  flowers  do 
not  propose  to  be  deprived  of  their  pollen,  so  they 
stretch  their  stems  until  their  flowers  also  reach  the 
surface.  To  do  this  nature  has  given  to  these  flow- 
ers a  long  slender  spiral  stem  (peduncles)  so  that 


SOME    WATER-PLANTS.  I/ 

they  can  expand  like  a  spiral  spring.  When  the 
fertile  flowers  have  received  the  pollen,  their  spring- 
like stems  contract  and  they  can  then  ripen  their 
fruit  tinder  water.  Eel-grass  is  also  known  as 
tape-grass  on  account  of  its  long  tape-like  leaves. 
In  the  regions  above  the  Chesapeake  Bay  it  is  aleo 
known  as  "wild  celery,"  where  it  is  the  favorite 
food  of  the  canvas-back  duck. 

Eel-grass  is  an  excellent  plant  for  aquaria.  Its 
interesting  habits  above  described  make  it  most 
interesting  to  observe. 

3.  Water-weed  or  Ditch-moss  (Fig.  6)  is  also  a 
good  plant  for  aquaria.      The  stems  are  submerged 
and   quite   long,    branching   and   very   leafy.      The 
leaves   are   linear,    opposite,    or  whorled,    and    are 
crowded  closely  together.      Each  leaf  has  a  simple 
vein   or   nerve   through   the   middle.      The  flowers 
are  rarely  seen,  but  like  the   eel-grass  they  are  of 
two  kinds  and  they  are  fertilized  in  much  the  same 
way.     The  fertile  flower  is  not  possessed  of  a  spiral 
stem  like  that  of  the  eel-grass,  but  it  reaches  the 
surface  by  the  elongation  of  the  calyx-tube.      Ditch- 
moss  has  a  rich  green  color  and  forms  a  most  de- 
sirable addition  to  any  aquarium.      If  exposed  to 
the  direct  rays  of  the  sun,  the  leaves  will  soon  be- 
come covered  with  bubbles  of  oxygen  which  glisten 
like  dew-drops  in  the  light. 

4.  Potamogeton  or  pondweed  (Fig.  7)  is  hardly 
desirable  in  small  aquaria  on  account  of  its  size,  for 


1 8        HOW    TO   TEACH    ABOUT    AQUATIC    LIFE. 

it  often  attains  a  growth  many  feet  long.  But  it  is 
an  interesting  plant  to  observe,  and  pieces  of  it  may 
be  placed  in  small  aquaria. 


FIG.  6. — Ditch-moss. 


There  are  many  species  of  pondweed,  but  the 
commonest  may  be  known  by  its  bright  green,  oval, 
floating  leaves  and  by  its  narrow  submerged  ones. 


SOME   WATER-PLANTS.  1 9 

The  flowers  are  small,  green  or  red,  and  clustered 
in  spikes.  These  spikes,  especially  in  their  fruit, 
usually  project  above  the  water  of  quiet  pools  and 
inland  lakes. 

Whether  pondweed  be  placed  in  the    aquarium 
or  not,  it  is  a  good  thing  for  teachers  to  be  able  to 


FIG.   7. — Pondweed. 

know  it,  for  in  summer  the  under  surface  of  its  float- 
ing leaves  will  usually  be  found  covered  with  minute 
animals  such  as  amoebae,  hydrae,  etc. 

Water-lily  leaves  are  also  good  places  to  look  for 
the  lower  forms  of  fresh-water  life. 

5.  Hornwort  (Fig.  8). — This  beautiful  aquatic 
plant  may  be  known  by  its  numerous  slender 


20        HOW   TO   TEACH   ABOUT   AQUATIC    LIFE. 

branching  stems  and  its  whorls  of  narrow  leaves. 
It  floats  in  the  water,  bearing  flowers  of  both  kinds 
which  are  very  small  indeed.  The  flowers  depend 
on  currents  of  the  water  to  fertilize  them. 


FIG.   8. — Hornwort. 


FIG.  9.— Water-wort. 


6.  Water- wort  or  mud-purslane  (Fig.  9)  is  so 
called  because  its  leaves  have  a  slight  resemblance 
to  the  purslane  of  "  pusley "  of  the  gardens.  It 


SOME   WATER-PLANTS. 


21 


grows  in  small  clusters  or  tufts  in  very  wet  places, 
being  sometimes  underwater  and  at  others  well  out 
of  it.  The  stems  are  stout  and  short  and  the  leaves 
thickish.  The  flowers  are  sessile  in  the  leaf-axils 
and  very  minute.  A  small  tuft  of  this  plant  looks 
well  in  the  bottom  of  an  aquarium. 

7.  Water-nut  or  water-milfoil  is  a  tropical  plant 
which  thrives  well  in  aquaria.      The  leaves  are  of 


FIG.   10. — Water-nut. 


two  kinds,  the  much  dissected  submerged  ones  and 
the  broad  egg-shaped  aerial  leaves.  This  plant 
floats  by  means  of  its  inflated  leaf-stems.  These  are 
enlarged  and  rilled  with  air.  Thus  the  plant  floats 
with  its  lower  leaves  in  the  water  and  its  roots  in 
the  mud.  It  can  only  be  had  at  the  greenhouses, 


22         HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

and  for  that  reason  is  not  so  desirable  as  our  native 
aquatic  plants. 

8.  Chara  or  stonewort. — The  mode  of  growth  of 
this  plant  and   especially  its  mode  of  flowering  or 
reproduction  is  too  complicated  to  enter  into  a  book 
of  this  kind,  but  the  plant   itself  is  a  desirable  one 
for  the  aquarium. 

It  grows  in  fresh  and  in  brackish  water,  where  it 
forms  in  great  masses  over  the  bottom.  The  stems 
arc  long,  cylindrical,  jointed,  and  much  branched. 
The  branches  give  off  whorls  of  thick  needle-shaped 
leaves  and  the  whole  plant  is  covered  with  a  crust 
of  lime  which  makes  it  rough  and  harsh  to  the  touch. 
This  lime  makes  the  plant  very  brittle,  hence  the 
name  stonewort. 

Chara  is  of  a  dull  green  color  bordering  on  olive. 
It  looks  very  pretty  in  an  aquarium. 

9.  Water-cress  grows  well  in  a  shallow  aquarium. 
It  is  too  well-known  to  need  a  description.      It  is 
the  well-known  cress  used  as  a  salad  and  sold  in  the 
markets.    Its  peppery  taste  proclaims  its  near  rela- 
tionship to  mustard  and  horseradish. 

10.  Green-slime.     The  foregoing  nine  plants  arc 
valuable  in  an   aquarium,   since   they  take  up   the 
carbonic    acid  gas    given    off    by  the  animals    and 
give  off  oxygen,  without   which  the  latter  cannot 
live.      But  whether  you  desire  it  or  not,  you  are 
sure  to  have  a  most  undesirable  guest  in  the  form 
of  a  plant  known  as  green-slime.      This  grows  on 


SOME   WATER-PLANTS. 


FIG.   IT.— Chara. 


24        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 


the  glass  and  also  on  the  rocks  within,  and  unless  it  is 
removed  the  glass  will  become  so  thickly  coated 
with  it  as  to  prevent  observations. 

But  nature  has  provided  a  way  of  removal  which 


FIG.   12. — Water-cress. 

is  as  interesting  as  it  is  instructive.  Among  the 
creatures  that  live  in  the  water  are  many  which  live 
on  green-slime.  These  are  the  water-snails.  No 
aquarium  is  complete  without  a  few  of  them.  They 
will  be  studied  in  the  second  part  of  this  book. 


CHAPTER    V. 
Some  Water-animals. 

THE  animal  life  of  the  water  may  be  divided  into 
three  classes.  These  are  first  those  whose  whole 
life  is  spent  in  the  water;  second,  those  whose  early 
life  is  spent  in  water  but  whose  mature  life  is  spent 
out  of  it ;  and  third,  those  who  at  certain  times  take 
to  the  water  while  at  others  live  on  the  land. 

To  the  first  class  belong  all  hydras,  most  fishes, 
and  certain  species  of  snails.  To  the  second  class 
belong  many  insects  such  as  the  mosquito,  dragon- 
fly, and  corydalis.  To  the  third  class  belong  the 
frogs,  toads,  newts,  and  some  turtles,  or  what  are 
commonly  classed  as  amphibrians. 

It  will  be  the  purpose  of  the  next  few  chapters  to 
study  some  of  these  creatures. 

I.  Fishes. — Select  some  fish,  no  matter  what 
kind  of  a  fish  it  is,  and  study  it  as  a  type.  Having 
made  a  thorough  study  of  one  fish,  others  will  be 
more  easily  observed. 

Observe  (a)  parts  (head,  body,  and  tail) ;  (b)  fins 
(one  or  two  dorsal,  two  ventral,  two  pectoral,  one 

25 


26        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

anal,  and  one  caudal);    (V)  gill-covers;    (d)  mouth; 
(r)  covering. 

Not  all  fish  are  possessed  of  all  the  fins  mentioned 


FIG.   13. — Shad. 

above,  but  all  have  pectoral  and  ventral  fins.  These 
represent  the  upper  and  the  lower  extremities. 
Most  fishes  have  three  other  fins.  These  are  one 
dorsal,  one  anal,  and  one  caudal  fin. 

Observe  the  fish  to  discover  how  he  swims.      It 


FIG.  14. — Cod. 

will  be  seen  that  it  is  due  to  the  motions  of  the 
caudal  fin  from  side  to  side,  just  exactly  as  an  oars- 
man propels  his  boat  with  a  single  paddle  astern, 


SOME   WATER- ANIMALS.  2/ 

and  not  to   any  action    of   the   lateral  fins.      These 
s^rve  to  balance  the  body  in  the  water. 

Next  study  the  gill-covers.    These  are  the  broad, 
rounded,  horny  plates  on  each  side  of  the  head  back 


FIG.  15.— Dorsal. 


of  the  eyes.  These  are  often  called  gills.  The 
real  gills  are  soft  red  fleshy  fringes  arranged  irr  rings 
or  arches  underneath  the  gill-covers.  The  mouth 
and  the  manner  of  breathing  should  be  observed. 
Notice  that  the  mouth  opens  as  the  gill-covers 
close  and  vice  versa.  In  this  way  the  water  enter- 
ing the  mouth  passes  back  over  the  gills,  washing 


28        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

them  and  supplying  them  with  oxygen  at  the  same 
time  that  it  carries  away  the  impurities. 

Fishes  do  not  drink.  What  appears  to  be  drink- 
ing is  really  breathing. 

Examine  the  covering  of  the  fish.      Most  fishes 


FIG.   16. — Caudal  Fins. 

are  clad  in  an  armor  of  shining  scales  which  overlap 
very  much  as  shingles  overlap  on  a  roof.  But  some 
fishes  have  no  scaly  covering,  as  may  be  seen  by 
studying  trout,  catfish,  and  eels.  In  others  the 
scales  are  so  small  as  to  be  scarcely  visible.  The 
scales  of  the  pike  and  the  trout  are  very  small 
indeed. 


SOME   WATER-ANIMALS.  29 

The  fins  and  tails  vary  greatly  in  structure  and  in 
form.  A  few  forms  are  submitted. 

GOLDFISH. 

Goldfish  are  so  common  in  aquaria  that  we  shall 
first  consider  them.  They  are  very  variable  in  size, 
some  attaining  a  length  of  fourteen  inches  and 


FIG.  17.— Goldfish. 

weighing  over  two  pounds.  They  are  usually  of  a 
deep  red-orange  color,  but  it  is  not  unusual  to  find 
them  almost  white  or  black  and  variously  mottled. 
Goldfish  are  easily  raised.  They  thrive  very  well 
in  confinement,  and  accustom  themselves  to  ponds 
very  easily.  At  Glen  Cove,  Long  Island,  the 
ponds  were  stocked  years  ago  with  goldfish  and 
they  are  still  very  numerous  there.  They  may 
frequently  be  seen  swimming  in  schools  through 
the  water, 


30      HOW  TO  TEACH  ABOUT  AQUATIC  LIFE. 

BROOK-TROUT. 

These  fishes  do  not  thrive  well  in  aquaria,  since 
they  need  fresh  running  water.  Indeed  any  one 
who  is  familiar  with  the  habits  of  brook-trout 
knows  that  their  favorite  haunt  is  where  the  water 
rushes  over  and  among  the  stones. 

It  is  difficult  to  describe  adequately  this  beauti- 


FIG.  18.  — Brook-trout. 

ful  fish.  The  male  and  the  female  are  about  the 
same  size,  being  about  a  foot  long  and  nearly  four 
inches  deep,  and  sometimes  weighing  over  four 
pounds. 

The  male  is  white  along  the  belly  and  colored 
with  bands  of  orange,  olive,  and  dusky  gray  at  the 
dorsal  side.  The  upper  portions  of  the  body  are 
variously  spotted  and  speckled,  and  there  are  several 
scarlet  dots  bordered  with  blue  along  the  sides. 

The  female  is  much  paler  than  the  male,  being 
white  below  and  having  no  orange  band. 

The  pectoral  fins  are  placed  low  and  there  are 
two  dorsal  fins,  the  hinder  one  being  very  small. 


SOME   WATER-ANIMALS.  3  I 

The  ventral,  pectoral,  and  anal  fins  are  tinged  with 
orange  or  scarlet. 

On  the  whole,  the  trout  is  a  very  beautiful  fish. 
Its  appearance  is  quite  in  keeping  with  its  reputa- 
tion for  gameness. 

SUNFISH. 

These  are  small  flat  oval-shaped  fishes  variously 
marked  with  red,  blue,  gold,  green,  and  black. 


FIG.   19. — Sunfish. 

They  abound  in  fresh-water  lakes  and  streams  and 
are  often  called  "pumpkin-seeds  "  because  of  their 
shape  and  small  size.  They  are  rarely  over  four  or 
five  inches  long.  But  although  they  are  very  bony 
they  are  excellent  eating.  In  an  aquarium  sunfish 
sometimes  show  signs  of  sickening.  This  may  be 
due  to  a  fish-disease  caused  by  growth  of  a  fungus. 


32        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

It  has  been  found  that  if  salt  water  be  added  slowly 
until  the  whole  is  brackish,  these  fungi  are  killed 
without  any  injury  to  the  fishes.  After  a  time  the 
water  may  be  gradually  replaced  with  fresh  water. 

BLACK  BASS. 

This  fish  is  reputed  to  be  able  to  change  its  color. 
Whether  this  be  true  or  not,  they  vary  greatly  in 
color,  having  black,  green,  or  yellow  sides  according 
to  circumstances.  The  gill-covers  have  two  flat 


FIG.  20. — Black  Bass* 

points  and  minute  teeth.  The  back  fin  is  single 
but  partly  divided  into  two  with  ten  hard  and  four- 
teen soft  rays.  Pectoral  fins  have  eighteen  soft  rays, 
ventral  fins  six  soft  rays,  and  anal  fins  three  spines. 
The  black  bass  belongs  to  the  perch  family. 
They  take  all  sorts  of  bait,  but  prefer  live  to  dead 
bait.  The  helagramite  is  a  favorite  bait.  In  June 
they  frequent  grassy  bottoms.  Later  they  are 
found  among  rocky  shoals. 


SOME  WATER- ANIMALS.  33 

YELLOW  PERCH. 

These  fishes  abound  in  northern  waters.  They 
are  yellow  in  color,  having  several  dark  vertical  bars 
over  the  back.  Fins  orange.  Gill-covers  are 
toothed  below  and  armed  with  long  spine.  Teeth 


FIG.  21. — Yellow  Perch. 

small.     The  fin-rays  are  as  follows:    Dorsal,  13,  2, 
15;   ventral,   i,  5;  anal,  2,  8;    caudal,   17. 

The  yellow  perch  spawns  in  April  and  May  rear 
the  shore  usually  in  water  one  foot  deep.  The 
flesh  is  coarse  white,  tasteless.  They  probably 
destroy  multitudes  of  young  trout. 

STRIPED  BASS. 

This  fish  is  a  favorite  with  fishermen.  It  is 
bluish  on  the  back,  lighter  on  the  sides  and  white 
on  the  belly.  Its  name  is  due  to  the  presence  of 


34        HOW    TO   TEACH    ABOUT    AQUATIC    LIFE. 

from  seven  to  nine  dark  lines  which  traverse  the 
sides  of  the  body.  Those  on  the  upper  side  extend 
to  the  tail,  while  those  on  the  ventral  side  fade  out. 
The  gill-covers  are  rough  like  the  edge  of  a  saw. 
They  have  two  spines  on  the  back.  The  ventral 
fins  are  lower  and  behind  the  pectorals. 

The  striped  bass  is  a  very  gamey  fish.  He  bites 
freely  and  fights  bravely  for  his  life.  This  fish 
varies  greatly  in  size  and  weight,  specimens  having 
been  captured  weighing  from  one  ounce  to  one 
hundred  pounds. 

Striped  bass  spawn  in  April,  running  up  rivers  to 
spawn.  They  return  to  salt  water  in  autumn,  when 
they  are  said  to  burrow  in  mud  or  hide  in  deep 
water  through  the  winter.  The  striped  bass  which 
are  bred  in  fresh  inland  waters  thrive  well  and  the 
flesh  has  a  better  sweeter  flavor. 

CATFISH. 

This  fish  is  familiarly  known  as  the  bullhead.  It 
is  also  called  the  horned  pout  because  of  the  numer- 
ous fleshy  tentacles  arranged  about  the  mouth. 
These  give  these  fish  a  formidable  appearance. 

It  is  common  in  fresh  water  east  of  the  Rocky 
Mountains.  It  is  black  on  the  back  and  white  on 
the  belly  and  its  head  is  very  large  in  proportion  to 
the  remainder  of  the  body. 

The  catfish  is  very  voracious,  eating  everything. 
It  is  very  tenacious  of  life  also.  In  spring  the  cat- 


SOME    WATER- ANIMALS.  35 

fish  spawns   and   the   female   is   said   to  watch   the 
young. 

Catfish  frequently  attain  to  an  enormous  size  and 
weight ;  one  huge  catfish  in  the  New  York  Aquarium 


FIG.  22.— Catfish. 

is  said  to  weigh  over  200  pounds.  Such  fish  are 
very  fat  and  the  flesh  is  very  strong  and  unfit  for 
food.  Young  fishes,  however,  are  most  delicious 
eating,  as  the  flesh  is  delicate  in  flavor  and  fine  in 
texture. 

They  are  prepared  for  the  table  by  skinning. 
The  skin  is  easily  removed  and  is  very  tough. 

WHITEFISH. 

This  is  one  of  the  handsomest  and  most  useful 
of  American  fishes.  As  the  name  indicates,  this 
fish  is  nearly  white,  being  colored  a  bluish  gray  only 
on  the  dorsal  aspect.  The  scales  are  large,  teeth 
minute  velvet-like,  body  narrow  compressed,  mouth 
very  small.  This  fish  abounds  in  the  Great  Lakes, 
where  it  is  caught  in  great  numbers.  It  often 


36        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

weighs  from  twelve  to  fourteen  pounds  and  is  the 
finest  fresh-water  fish. 


TROUT. 

This  fish  is  the  sportsman's  fish  par  excellence. 
It  never  thrives  in  aquaria.  The.,  shoulder  and  the 
first  dorsal  fins  have  eleven  rays,  the  ventral  eight, 
anal  fifteen,  and  caudal  nineteen. 

The  back  is  dusky  green,  mottled  with  brilliant 
yellow  spots  on  the  sides,  interspersed  with  blue 
and  red  dots.  The  belly  is  silver-white  tinged  with 
rose-color.  The  body  appears  at  first  to  be  naked, 
but  on  close  examination  it  is  seen  ,to  be  covered 
with  very  minute  scales.  The  tongue  and  throat 
are  covered  with  teeth.  The  trout  prefers  the 
limpid  waters  of  a  brook,  where  he  may  swim  about 
among  the  rocks.  As  an  article  of  food  no  fish 
surpasses  the  trout  in  delicacy  of  flavor. 

2.  Mollusks  or  Shellfish.  Snails. — These  crea- 
tures may  be  divided  into  two  great  groups  depend- 
ing on  the  number  of  their  shells.  These  are  uni- 
valves or  mollusca  having  one  shell  and  bivalves  or 
mollusca  having  a  pair  of  shells  joined  by  a  hinge 
and  fitting  closely  together. 

The  commonest  fresh-water  mollusks  are  the 
snails,  and  of  these  there  are  many  species.  We 
will  consider  only  two  of  the  common  forms,  because 
both  are  readily  found  creeping  over  rocks  ancj 


SOME   WATER-ANIMALS.  3/ 

submerged  stems  in  their  search  for  tender  green- 
slime,  which  forms  their  principal  food. 

Their  shells  are  of  two  general  forms,  the  spiral 
(a)  and  the  conical  (£).  In  various  species  the  shell 
varies  between  these  forms  and  these  animals  vary 
in  size  from  very  tiny  creatures  scarcely  larger  than 
a  pin-head  to  more  than  an  inch  in  diameter. 

Wate-rsnails  are  not  water-breathers.  They  have 
no  gills,  but  they  have  the  simplest  form  of  lung. 


FIG.  23.— Snails. 

To  prevent  the  entrance  of  water  the  nostril  closes 
with  a  lid.  If  watched  for  some  time  water-snails 
will  be  seen  to  go  to  the  surface  and  thrust  the 
head  above  it.  This  is  to  breathe.  If  a  plant  or 
bit  of  rock  project  above  the  water,  the  snails  will 
often  go  up  and  remain  for  some  time  in  the  air. 

If  green-slime  is  growing  upon  the  glass  of  the 
aquarium,  water-snails  will  soon  be  found  crawling 
over  it  and  their  manner  of  locomotion  can  easily 
be  observed.  The  portion  which  they  thrust  from 
the  shell  is  called  the  foot.  It  is  a  soft  muscular 


38         HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

body  and  it  acts  like  the  ordinary  leather  "  sucker" 
in  holding  the  snail  to  the  glass.  If  observed 
closely  the  wave-like  vibration  in  this  foot  will  be 
seen  as  the  snail  advances  across  the  glass. 

Pond-snails  are  unlike  land-snails  in  having  no 
eye-stalks.  Their  eyes  are  located  at  the  base  of 
their  feelers. 

FRESH-WATER  MUSSELS. 


FIG    24. — Diagram  of  Fresh-water-mussel  Shell. 
Over  the  bottoms  of  fresh-water  ponds  one  may 
often   see  long  lines  or  scratches  in  the  soft  mud. 


SOME    WATER-ANIMALS. 


39 


These  marks  look  not  unlike  the  tracks  made  across 
muddy  road-beds  at  night  by  the  familiar  earth- 
worm or  angle-worm.  If  followed  with  the  eye  for 
some  distance  a  fresh-water  mussel  will  usually  be 
found  \\ith  its  hinge-line  uppermost.  The  track 
has  been  made  with  its  tough  fleshy  foot. 

The  mussel-shell  is  broad  and  convex.  The 
lines  of  growth  are  very  plain.  The  shell  is  cov- 
ered with  a  horny  layer  of  a  dull  olive- brown  color. 
Within  the  shell  is  pearly  and  shows  several  muscu- 
lar impressions.  There  are  several  species  of  mus- 
sel, some  having  very  beautifully  colored  shells. 

CLAMS. 

Clam-shells  resemble  those  of  the  fresh-water 
mussel  somewhat  in  shape  and  size,  but  they  are 


FIG.  25.  — Clam-shell— Exterior  View. 


40        HOW   TO    TEACH   ABOUT   AQUATIC    LIFE. 


FIG.  26.— Interior  View  of  Clam  Shell 


FIG.  27.— View  of  Clam— Both  Valves  Open. 


SOME    WATER- ANIMALS.  4! 

thicker,  heavier,  and  whiter  in  color.  The  lines  of 
growth  also  are  more  prominent.  There  is  no 
horny  growth  on  the  outside  of  clam-shells.  The 
inner  surface  of  the  valves  shows  only  two  mus- 
cular impressions.  The  inside  is  also  smooth  but 
not  pearly,  and  the  lines  of  growth  are  not  to  be 
seen.  Near  the  edge  of  the  clam-shell  is  a  well- 
marked  line,  just  as  there  is  in  the  fresh.-water- 
mussel  shell,  but  in  the  latter  it  is  parallel  with  the 
edge,  while  in  the  former  this  line  bends  inward, 
forming  a  deep  notch. 

Clams  bury  themselves  in  the  sand  at  the  sea- 
bottom,  whence  they  are  brought  forth  by  means 
of  long-handled  tools  known  as  clam-tongs.  Un- 
like the  fresh-water  mussel,  clams  do  not  travel. 
Soft-shell  clams  resemble  the  foregoing.  They  are 
dug  out  of  the  sand  at  low  tide. 

The  clam  is  a  good  creature  to  study  as  a  type, 
since  it  stands  at  the  head  of  the  class  among 
animals. 

SCALLOPS. 

These  are  well  known  on  account  of  their  great 
delicacy  and  beautifully  shaped  shells.  Scallops, 
unlike  the  preceding  mollusks,  do  move  about,  and 
that  very  rapidly.  They  do  this  by  means  of 
opening  and  shutting  their  valves.  This  forces  the 
water  out,  and  the  jet  acting  against  the  still  water 
beyond  forces  the  scallop  forward  with  a  rapid 


42         HOW   TO    TEACH    ABOUT    AQUATIC    LIFE. 

motion.  Scallops  are  also  noteworthy  in  being 
the  fortunate  possessors  of  numerous  steel-black 
eyes. 

The  only  part  of  the  scallop  eaten  is  the  thick 


FIG.  28. — Scallop. 

muscle  which   forms    the  body  of   the    animal   and 
holds  the  valves  together. 

Scallops  seem  to  migrate  in  vast  numbers,  so 
that  waters  which  teem  with  them  this  year  may 
not  furnish  any  a  year  hence. 

SEA-MUSSEL. 

The  sea-mussel  is  not  at  all  like  the  fresh-water 
mussel.  The  shell  is  of  a  dark  blue  or  blue-black, 
marked  with  fine  parallel  marks.  It  is  narrow  and 
deep  and  lined  with  a  thin  layer  of  white,  pearly 


SOME  WATER-ANIMALS.  43 

material.  The  most  striking  feature  is  the  byssus 
or  threads  which  the  sea  mussel  thrusts  out  and 
fastens  to  rocks,  stones,  and  other  shells. 

It  is  no  unusual  thing  to  find  a  dozen  or  more 
sea-mussels  all  joined  in  a  tangled  mass  with  gravel 


FIG.  29. — Sea-mussel. 

and  other  shells  by  means  of  these  tough  elastic 
fibres. 

Sea-mussels  attach  themselves  to  piles  and  other 
timbers  at  high  tide,  and  then  they  may  be  seen 
when  the  tide  has  gone  out  hanging  high  and  dry 
above  the  beach. 

Mussels  are  not  very  highly  prized  for  food,  but 
some  people  spice  them  in  vinegar,  and  then  they 
are  regarded  as  a  delicacy. 

OYSTERS. 

The  oyster  should  not  be  studied  until  many 
other  mollusks  have  been  observed.  It  is  an  er- 
ratic form,  and  should  therefore  be  studied,  if  at 
all,  after  the  general  features  of  normal  mollusca 
are  well  known. 


44        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

The  oyster-shell  varies  greatly  in  shape  and  size. 
Large  numbers  of  shells  frequently  are  found  grow- 
ing together  in  masses.  The  outside  shows  many 


FIG.  30. — Oyster. 

overlapping  layers  of  calcareous  matter.  The 
hinge  is  small.  The  valves  are  very  unlike  in 
shape,  one  being  larger  and  deeper  than  the  other. 
Inside  one  sees  only  one  large  muscular  impression. 

PERIWINKLES. 

Periwinkles    are     among    the    commonest    shells 
washed   on    our   shores       Some   are   of  a   dull-gray 


SOME    WATER-ANIMALS.  45 

color  and  smooth,  while  others  are  of  a  delicate 
salmon  hue  and  covered  with  a  membrane.  This 
skin  is  beset  with  fine  fringes  resembling  the  pile 
of  velvet.  Their  eggs  are  among  the  most  curious 
things  washed  up  by  the  sea.  The  egg  mass  con- 
sists of  a  long  string  of  flat,  purse-shaped  sacs, 
each  of  which  contains  a  large  number  of  tiny 
periwinkles. 

Periwinkles  are  among  the  greatest  cnemLs  of 
the  oysters,  and  oystermen  take  every  precaution 
to  destroy  them. 

RAZOR-SHELLS. 

These  are  interesting  mollusks  on  account  of 
their  peculiar  shells,  which  are  shaped  very  much 
like  a  razor.  They  burrow  in  the  sand  very  much 
as  clams  do  and  are  eaten  by  some  people. 


FIG.  31. — Razor-shell. 

The  shell  is  much  more  brittle  than  that  of  the 
clam.      It  resembles  the  mussel-shell  in  structure. 
3.  Other  Creatures  of  the  Water. 

HYDRAS. 

If  the  stones  from  the  bottom  of  a  fresh-xvater 
stream  be  examined  closely,  tiny  patches  of  green 


46        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

or  red  matter  may  be  seen  upon  them.  At  first 
these  may  be  mistaken  for  green-slime  or  a  fungoid 
growth,  but  if  watched  for  some  time  the  mass  will 
expand  into  a  tiny  funnel-formed  shape,  and  closer 
examination  with  a  magnifying-glass  will  show  a 
circle  of  dainty  tentacles  around  the  upper  side. 


FIG.  32. — Hydra  (Magnified). 

If  the  vessel  be  given  a  slight  jar,  the  tentacles 
will  be  drawn  in  and  the  whole  creature  assume  its 
original  shapeless  form. 

The  base  of  the  creature  is  called  the  foot.  It 
acts  like  a  sucker  to  hold  the  hydra  in  place.  But 
the  hydra  is  not  by  any  means  incapable  of  loco- 
motion. If  observed  for  a  long  time,  hydras  will 
be  seen  to  creep  from  one  place  to  another.  This 
creeping  is  a  most  interesting  act.  It  is  nothing 
else  than  a  series  of  somersaults.  The  hydra  first 
places  his  head  (if  one  may  say  that  a  headless 
creature  has  a  head)  upon  the  stone  near  his  foot 
and  takes  hold.  Then  it  lets  go  with  the  foot  and 
turns  over.  By  repeating  this  act  the  hydra  at 
length  comes  to  the  place  where  it  desires  to  go. 

The  hydra  belongs  to  a  great  class  of  creatures 


SOME   WATER-ANIMALS.  47 

which  may  be  called  radiates,  because  the  parts  of 
their  bodies  radiate  from  a  centre. 

SOME  OTHER  RADIATES. 

The  best-known  radiate  is  the  starfish.      Its  five 
strong,  rorgh  arms,  its  multitude  of  feet,  its  mouth 


FIG.  33. — Starfish. 

armed  with  five  sharp  teeth  and  its  strainer  are  all 
easily  found.  Its  manner  of  eating  oysters  is  not 
so  generally  known.  But  oystermen  recognize  in 
the  starfish  the  very  worst  enemy  of  their  trade. 


48        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

The  starfish  walks  over  the  bottom  on  the  tips  of 
its  pointed  arms.  On  reaching  an  oyster  whose 
shell  is  open  the  starfish  projects  its  stomach  out  of 
its  mouth,  scoops  the  oyster  from  his  shell,  and 
devours  him  before  he  can  close  his  valves.  Many 
starfishes  do  not  succeed  in  getting  the  oyster  from 
his  shell.  In  the  inevitable  struggle  his  brittle 
arms  are  in  great  danger  of  being  broken  off. 
This  would  be  a  sad  calamity  to  one  of  the  higher 
animals,  but  the  starfish  cannot  care  much  about 
it,  for  in  time  a  new  arm  will  grow  on. 

Sometimes  the  starfish  is  broken  so  near  the  cen- 
tral disk  that  two  arms  will  grow  where  the  one  was. 
In  this  way  some  monsters  are  often  found.  The 
writer  has  in  his  collection  starfishes  having  three, 
four,  five,  six,  and  eight  arms,  and  a  friend  has 
starfishes  having  every  number  of  arms  from  one  to 
ten. 

Small  streams  and  shallow  pools  of  sea-water 
where  the  tide  comes  in  and  out  will  usually  be 
found  to  contain  polyps.  These  are  curious  crea- 
tures resembling  hydrae  in  some  respects,  but  very 
much  larger.  They  consist  of  cylindrical  masses  of 
jelly,  having  a  mouth  at  the  centre  of  the  top  sur- 
rounded by  many  delicate  feelers.  If  disturbed 
these  curious  animals  at  once  contract  into  a  shape- 
less mass  of  jelly.  For  the  benefit  of  those  who 
may  want  to  preserve  polyps  the  following  recipe  is 
submitted :  Place  the  stone  on  which  the  polyp  is 


SOME   WATER-ANIMALS.  49 

growing  in  a  glass  of  sea-water.  It  will  of  course  con- 
tract into  a  globular  mass  at  first,  but  after  a  time  it 
will  expand  to  its  full  size  and  extend  its  thread-like 
tentacles.  Then  add  a  drop  of  magnesium  sulphate 
solution,  then  another  and  another,  very  slowly, 
being  careful  not  to  jar  the  vessel.  If  done  properly 
the  creature  will  presently  become  paralyzed,  with 
its  body  full  size  and  tentacles  extended.  Then  add 
a  small  quantity  of  chromic  acid  to  kill  the  polyp. 


FIG.  34.— Polyp. 

After  the  animal  is  dead,  pour  out  about  one- 
tenth  of  the  sea- water  and  add  the  same  amount  of 
formaldehyde,  or  "formalin"  as  it  is  called,  to 
preserve  the  specimen.  Alcohol  is  just  as  good  for 
preserving  specimens,  but  it  costs  a  great  deal  more. 

4.  The  Crayfish  and  his  Cousins. — The  crayfish 
is  so  common  as  to  need  no  extended  description. 
The  most  conspicuous  features  are  the  huge  front 
claws  like  pincers,  the  long  feelers  or  antennae,  and 
the  flat  tail.  The  body  is  made  up  of  joints  or 
rings  covered  with  hard  horn-like  substance.  There 
are  ten  jointed  legs,  hence  this  family,  to  which 


50        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

crayfish  belong,  is  called  decapoda,  a  word  meaning 
ten  feet.  The  gills  are  under  the  broad  thorax- 
shell.  The  mouth  is  armed  with  a  beak.  The  eyes 
are  compound  and  stalked  so  that  the  crayfish  can 
project  them  up  and  see  in  all  directions. 

The  most  interesting  trait  of  this  animal  is  his 
way    of    locomotion.      He    goes    backwards    rather 


FIG.  35. — Crayfish. 

than    forwards    by    shooting   himself   through    the 
water. 

Every  aquarium  should  have  one  or  more  cray- 
fishes, but  they  are  best  kept  by  themselves,  as  they 
sometimes  devour  the  other  denizens  of  the  aqua- 
rium. Crayfishes  are  usually  quite  abundant  in 
small  clear  streams,  where  they  may  be  caught 
creeping  about  among  the  stones  on  the  bottom. 

OTHER  CRUSTACEANS. 

There  are  many  relatives  of  the  crayfish,  but 
most  of  them  live  in  the  sea.  Among  these  are  the 


SOME    WATER-ANIMALS.  5! 

crab,  the  lobster,  and  the  shrimp,  so  highly  valued 
for  food.  But  there  are  many  others  which  are 
among  the  most  curious  inhabitants  of  the  sea- 
shore. Among  these  are  the  fiddler-crab.  One  of 
its  front  claws  is  very  large,  while  its  mate  is  small. 
It  thus  gives  him  the  appearance  of  a  man  playing  a 
"  fiddle."  This  crab  lives  in  vast  numbers  near 
the  seaside,  where  it  burrows  in  the  ground.  The 
female  has  both  front  claws  alike,  and  both  are  small. 

The  hermit-crab  is  also  a  very  curious  creature. 
It  lives  in  the  abandoned  shells  of  sea-snails. 
When  it  grows  too  large  to  live  in  its  borrowed 
house  in  comfort,  it  creeps  out  and  seeks  a  larger 
shell.  By  living  in  a  shell  all  the  time  the  hind 
parts  of  the  body  become  soft  and  unprotected  by 
horny  scales  like  those  of  its  cousins. 

The  king  crab,  or  horseshoe  crab,  is  not  really  a 
crab  at  all.  It  is  the  sole  descendent  of  a  mighty 
race  of  creatures  which  once  inhabited  the  waters 
of  the  earth — the  trilobites.  It  has  a  smooth 
rounded  horn-like  shell  in  which  are  two  huge  com- 
pound eyes  and  two  simple  eyes.  Underneath  are 
six  pairs  of  jointed  legs.  The  body  is  tipped  with 
a  long  needle-like  spine. 

King  crabs  are  mostly  nocturnal.  They  come 
along  the  shore  as  the  tide  comes  in  and  devour  all 
sorts  of  organic  matter  cast  up  by  the  waves. 

Sand-fleas  and  water-fleas  are  tiny  crab-like  crea- 
tures which  are  often  found  in  water  and  in  wet 


52         HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

sandy  beaches.  They  are  easily  caught,  and  if 
placed  in  a  glass  of  clear  water  they  may  be  observed 
for  a  long  time. 

In  regard  to  preserving  crustaceans  it  is  well  to 
know  that  most  of  these  animals  have  the  power  of 
throwing  off  their  legs  if  they  are  placed  in  alcohol 
or  formalin  suddenly.  This  is  because  these  sub- 
stances hurt  them  and  produce  a  muscular  contrac- 
tion so  violent  as  to  break  them  at  the  joints.  To 
prevent  this  it  is  better  to  let  the  water  get  slowly 
warm  until  it  is  so  hot  as  to  kill  them.  Then  the 
preserving  fluid  may  be  added,  and  the  specimen  is 
ready  for  the  collection. 

NOTE. — Teachers  who  live  inland  too  far  from 
the  sea  to  study  marine  life  may  spend  a  summer 
at  the  shore  and  then  make  a  collection  for  use  in 
school  during  the  year.  I  would  urge  any  and  every 
such  teacher  to  provide  herself  with  a  quantity  of 
bottles  and  a  supply  of  alcohol  or  formaldehyde 
and  make  a  collection  even  if  she  does  not  contem- 
plate making  an  exhaustive  study  of  such  things. 


We  have  thus  far  studied  a  few  creatures  the 
whole  of  whose  lives  are  spent  in  the  water. 
They  all  grow  from  eggs,  and  they  hatch  out  into 
forms  like  their  parents.  But  there  are  other  crea- 
tures whose  early  life  is  spent  in  the  water,  but 
whose  mature  life  is  spent  in  the  air.  It  will  be 
our  purpose  next  to  consider  a  few  of  these  animals. 


CHAPTER  VI. 
Metamorphosis. 

NOT  all  creatures  are  perfect  when  first  hatched. 
Very  few  come  forth  from  the  egg  in  perfect  con- 
dition. The  majority  pass  through  a  great  variety 
of  forms  before  they  attain  to  the  adult  state. 

We  have  considered  some  of  these  changes  in  the 
volumes  of  this  series  pertaining  to  insects,  but  meta- 
morphosis is  not  confined  to  insects.  With  those 
creatures  whose  life  is  spent  in  the  air  we  have 
nothing  to  do,  but  with  those  some  of  whose  life- 
changes  transpire  in  the  water  we  have  some 
concern. 

It  has  been  stated  in  another  volume  that  insect 
life  may  be  divided  into  four  principal  stages,  i.e. 
egg,  larva,  pupa,  imago.  Now,  insects  whose  early 
life  is  spent  in  the  water  are  found  to  pass  through 
the  same  stages,  but  in  the  larval  stage  they  are 
called  nymphs.  Thus  the  water-insect  is  said  to 
pass  through  the  following  stages:  egg,  nymph, 
pupa,  imago. 

With  this  last  stage  we  have  nothing  to  do,  since 

53 


54        HOW   TO    TEACH    ABOUT   AQUATIC   LIFE. 

it  is  the  stage  after  the  creature  has  left  the  water. 
But  with  the  stages  spent  in  the  water  we  may  very 
properly  concern  ourselves. 

In  collecting  material  for  the  aquarium  many 
living  creatures  will  be  found  which  do  not  belong 
to  any  of  the  types  previously  considered.  These 
may  be  roughly  divided  into  two  classes,  i.e.  those 
having  jointed  bodies  (nymphs)  and  those  having 
soft  more  or  less  fish-like  bodies  (amphibians). 

We  will  first  consider  a  few  of  the  nymph  or 
larval  forms. 

I.  The  Dragon-fly.  —  The  nymphs  are  easily 
recognized  as  insects.  They  have  a  three-parted 


FIG.  36. — Dragon-Fly. 

body  (head,   thorax,  and  abdomen),   six  legs,  and 
prominent  compound  eyes. 

The  wings  are  not  developed,  but  close  observa- 
tion will  discover  them  folded   away  on   the  back 


METAMORPHOSIS. 


55 


but  concealed  under  the  outer  shell  of  the  creature. 
They  vary  greatly  in  size  and  shape.  Some  have 
very  stout  bodies,  powerful  legs,  and  large  heads, 
while  others  are  long  and  slender  with  very  long 
slender  legs  and  abdominal  appendages.  Their 
mouths  are  large  and  have  very  large  lower  lips. 


FIG.  37. — Dragon-Fly  Nymph. 

They  shed  their  skins  several  times  before  attain- 
ing to  their  adult  size.  When  full  grown  they 
crawl  up  the  side  of  the  aquarium,  or  better  the 
stem  of  some  plant  growing  therein,  and  having 
dried  off  somewhat  they  emerge  from  their  skins  by 
creeping  out  through  a  split  down  the  back,  very 
much  as  a  man  gets  out  of  a  shirt. 

Nymphs  are  easily  captured  for  the  aquarium  by 
drawing  ashore  submerged  trash  with  a  garden-rake. 
The  nymphs  will  usually  be  found  crawling  around 
among  the  wet  trash. 

2.  The  Mosquito. — Wiggles  are  best  bred  in  an 
individual  aquarium  made  by  dipping  a  tumbler  or 
Mason  jar  part  full  of  rain-water  containing  them. 


56        HOW   TO   TEACH    ABOUT   AQUATIC   LIFE. 


METAMORPHOSIS.  57 

If  this  improvised  aquarium  is  kept  covered 
with  a  piece  of  gauze  or  netting,  the  development 
of  the  mosquitoes  may  be  studied  from  egg  to 
imago. 

In  collecting  larvae  of  mosquitoes  go  to  a  con- 
venient rain-water  barrel  or  'tub  which  contains 
them  ;  look  for  the  tiny  egg-masses  or  rafts  which 
may  be  found  floating  upon  the  surface. 

The  larvae  are  interesting  as  they  go  wiggling 
hither  and  thither  through  the  water,  and  the  pupae 
are  not  hard  to  recognize  on  account  of  their  large 
heads  and  less  active  movements. 

Mosquitoes,  nymphs,  and  other  insect  larvae  can- 
not be  bred  advantageously  in  aquaria  with  fishes  or 
indeed  with  each  other,  for  the  weaker  invariably 
must  succumb  to  the  stronger.  It  is  no  uncommon 
occurrence  to  find  many  of  the  inhabitants  missing 
after  a  few  days. 

3.  Stone-flies. — These  most  interesting  creatures 
are  usually  found  in  clear  running  water.  They 
are  so  called  because  they  live  in  cases  made  of  tiny 
stones  or  sticks.  These  cases  are  often  built  with 
consummate  masonry,  the  pebbles  being  selected 
with  greatest  care  and  cemented  together  with  a 
secretion  from  the  tiny  creature.  These  cases  are 
usually  about  £  to  I  in.  long  and  £  to  T3B-  in.  in 
diameter,  open  at  one  end,  from  which  the  legs, 
head,  and  antennae  may  be  seen  projecting. 

At  first  sight  nothing  is  more  interesting  than  to 


58        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

see  these  dainty  stone  cylinders  moving  about  over 
the  bottom  of  a  stream. 

The  stone-fly  does  not  thrive  well  in  aquaria 
unless  the  water  is  constantly  changing.  If  the 
water  becomes  too  warm  or  stale  these  creatures 
creep  forth  from  their  little  homes  and  die. 

When  ready  to  leave  the  water,  they  creep  out  of 
their  little  shelters  and  crawl  up  the  stems  of  some 
aquatic  plant.  In  the  air  they  soon  dry  off  and  the 
shell  cracks  down  the  back.  Then  the  imago  extri- 
cates itself  very  much  as  the  dragon-fly  does. 

4.  The  Dobson. — Everybody  has  seen  this  hid- 
eous-looking creature,  but  he  is  better  known  as  the 


FIG.  39. — Dobson. 

Hellgramite.  To  catch  these  curious  animals  pro- 
cure a  piece  of  thin  soft  cloth ;  mosquito-netting  is 
the  best.  Take  a  piece  perhaps  one  yard  square 


METAMORPHOSIS.  59 

and  go  to  some  rocky  brook  where  the  water  flows 
rapidly  over  the  stones.  Place  the  netting  in  the 
stream  so  that  it  will  float  out  flat  in  the  current. 
Lay  some  large  stones  at  the  upper  corners  so  that 
the  stream  shall  not  carry  it  away.  Then  go  up- 
stream a  few  feet  or  yards  and  begin  turning  over 
stones  in  the  bed.  Plenty  of  dobsons  will  be  set 
free.  They  will  be  borne  down-stream  until  they 
reach  the  mosquito-netting.  Here  they  will  be 
able  to  catch  hold  by  means  of  their  legs  and  man- 
dibles. In  the  central  States  dobsons  caught  in  this 
way  are  used  as  bait  for  bass. 

The  head  is  large,  thorax  conspicuous,  and  ab- 
domen long,  each  ring  being  armed  with  two 
spines.  The  jaws  are  also  large  and  powerful. 
The  dobson  is  thus  a  very  formidable  enemy  of  the 
larvae  of  stone-flies,  may-flies,  dragon-flies,  and 
other  water-loving  insects. 

With  the  pupa  and  imago  states  we  have  nothing 
to  do.  In  the  pupa  state  the  dobson  leaves  the 
water  and  forms  a  burrow  on  the  shore,  where  it 
remains  for  two  or  three  weeks.  Then  it  assumes 
the  imago  state,  known  as  Hellgramite  or  long- 
horned  corydalis,  and  flies  away. 

The  imago  is  not  seen  often,  because  it  is  noc- 
turnal in  its  habits,  but  it  is  readily  recognized  by 
its  broad  gray  wings  and  long  horns  and  antennae, 
its  prominent  head  and  neck-like  thorax. 


60        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

5.  Water-beetles.  —  No  aquarium  is  complete 
without  one  or  more  water-beetles.  These  are 
very  various  and  numerous.  They  may  be  recog- 
nized by  their  shining,  smooth,  shell-like  elytra 
and  their  curious  paddle-like  feet.  By  means  of 


FIG.  40. — Water-beetle. 

these  paddles  they  are  able  to  skim  rapidly  over 
the  surface,  and  some  species  dive  below  and  creep 
along  over  the  bottom. 

6.  Water-boatman. — This  is  a  hemipterous  in- 
sect (bug)  which  circles  about  on  the  water.  They 
are  usually  seen  in  great  numbers,  forming  patches 
of  silvery  sheen,  which  move  about  with  great 
rapidity.  The  hind  legs  are  essentially  similar  to 
those  of  the  water-beetles,  being  broad,  paddle- 
like,  and  armed  with  a  fringe  of  close-set  hairs 
along  their  posterior  margin. 


METAMORPHOSIS.  6 1 

7.  The  Ranatra. — The  ranatra  or  scorpion-bug 
has  been  mentioned  in  No.  8  Manual  of  this  series. 
It  is  one  of  the  strangest  creatures,  having  only 
four  legs,  used  for  walking  and  skimming  over  the 
surface,  while  the  prolegs  are  wonderfully  devel- 
oped into  organs  fitted  for  seizing  prey,  like  those 
of  the  scorpion  and  lobster. 


CHAPTER    VII. 
Some  Amphibians  and   Reptiles. 

AMPHIBIANS  are  cold-blooded  creatures  which 
begin  life  as  fishes,  breathing  by  means  of  gills, 
but  later  in  life  they  develop  true  lungs  and  be- 
come air-breathers.  To  this  class  belong  newts, 
frogs,  and  toads. 

I.  The  Frog. — The  eggs  are  laid  in  masses  con- 
sisting of  clear,  transparent  jelly  containing  small 
spherical  yolks  scattered  through  it. 

If  kept  in  a  vessel  of  fresh  water  these  yolks  will 
soon  show  the  formation  of  a  tiny  fish-like  body, 
which  soon  will  be  seen  to  move  from  time  to  time. 
At  length  the  enclosing  membrane  breaks  and  the 
tadpole  escapes  from  the  egg-mass. 

Tadpoles  are  of  a  dull-green  color,  and  from  the 
first  they  are  very  active.  They  resemble  fishes  in 
shape  and  motion,  but  show  no  signs  of  fins. 

They  grow  rapidly,  and  at  length  show  swellings 
on  each  side  well  back  towards  the  tail.  These  at 
length  open  up,  setting  free  a  pair  of  legs.  The 
same  is  repeated  soon  after  on  each  side  of  the 
head,  and  a  second  pair  of  legs  appears.  The  tail 
now  begins  to  shorten.  The  substance  seems  to 
be  absorbed  by  the  body,  and  the  outer  parts 
slough  off  and  drop  away,  leaving  the  creature 

62 


SOME    AMPHIBIANS    AND  REPTILES.              63 

without   any   vestige   of   a  tail.  The   tadpole   has 
become  a  frog. 

About  the  time  when  the  legs  are  appearing  the 


FIG.  41. — Frogs. 

tadpole  frequently  swims  to  the  surface  and  swal- 
lows air.  The  gills  are  gradually  disappearing  as 
the  lungs  are  developing. 


64        HOW    TO    TEACH    ABOUT    AQUATIC    LIFE. 

2.  The  Toad. — The  development  of  toads  is  ex- 
actly similar  to  that  of  frogs.      The  eggs  are  not 
laid  in  masses,  as  with  frogs,  but  in  strings  of  jelly 
having    the    yolks    arranged    uniformly    along    the 
strings.      These  yolks  are  black  in  toads,  and  toad- 
tadpoles  are  easily  told  by  their  black  color. 

When  fully  developed,  toads  leave  the  water  and 
return  to  it  only  at  spawning  time. 

3.  Newts. — Newts  pass   through   only   a  partial 
metamorphosis.      They  develop  legs,  but  they  do 
not  lose  their  tails,  and  they  never  go  far  from  the 
water.      Newts  frequent  small  streams,  the  outlets 
of    springs,   and    wet,    swampy    localities.      Unlike 
frogs  and  toads,  they  do  not  like  stale  water,  and 
will  die  if  the  water  is  not  kept  perfectly  fresh. 

4.  The  Turtle. — The  only  reptile  which  is  likely 
to  find  place  in  an  aquarium  is  the  turtle.     Turtles 


FIG.  42. — Snapping  Turtle. 

are  too  well  known  to  need  description  here. 
Their  shell-like  covering  and  beak-like  mouth, 
their  scaly,  clawed  feet  and  bright,  shining  eyes 
have  been  recognized  by  every  schoolboy.  Let  it 
not  be  forgotten  that  there  are  land-turtles  as  well 
as  water-turtles,  and  it  is  cruelty  to  animals  to 
place  land-turtles,  tree-toads,  etc.,  in  aquaria. 


V[j  36048 


